The interstitial lung disorders represent 15 to 20 percent of all pulmonary disorders; in most cases these diseases cause significant disability and many are fatal. Studies of the natural history, etiology, pathogenesis, pathophysiology and therapy of these disorders have made major inroads into understanding these diseases. Most importantly is the development of the concept that the inflammatory and immune effector cells are critical determinants in the pathogenic process. Methodologies have been developed to evaluate the alveolitis of these patients and to the examine its effect on the alveolar structures. Therapeutic trials are underway to evaluate the efficacy of drug programs aimed at irradicating the alveolitis of the diseases. Smoking induces macrophages to produce chemotactic factors for neutroiphils. In addition, cigarette smoke reduces the ability of alphal-antitrypsin to function normally. Therapeutic trials are ongoing for treatment of alphal-antitrypsin deficiency using Danacol therapy to increase release of the antiprotease from the liver and a direct replacement trial of alphal-antiproteinase is ongoing.